Caption: Vaccinia virus infected cell. Immunofluorescence deconvolution micrograph of a cell infected with vaccinia virus particles. Host and viral DNA (deoxyribonucleic acid) is pink. The host cell's DNA is contained within its nucleus (large oval at centre). The pink area above the nucleus is filled with viral factories. Actin protein filaments, which make up part of the cytoskeleton, are green. The cytoskeleton maintains the cell's shape and is involved in intracellular transport. The protein crk2, which is involved in intracellular signal transduction is red. Vaccinia causes cowpox, a disease of cattle and humans, which produces skin lesions.